Radar, digital communications, and other wireless systems require a precisely controlled gain in each channel to ensure a constant noise level. A fixed noise level is crucial for choosing thresholds that provide the desired balance between minimum signal detection and false alarms due to noise. The RDR-4000 radar system has a number of channels that operate over a 40 MHz bandwidth and requires that the noise level be controlled to 0.1 dB to maintain an acceptable false alarm rate. This is a difficult control problem given that the noise level can change by more than 1 dB on each scan due to tilt changes, numerous interfering signals, and the gain varying across the frequency band by up to 1 dB from the first to last channel. Furthermore, the total gain variation due to component variation, temperature changes, and multiple installation configurations is estimated at 8 dB in a worst case scenario. Typical approaches to this problem are channelized solutions which are not as efficient or even practicable for a large number of channels given the time constraints.
Therefore, there exists a need for controlling the noise level across all the channels.